MIKE PIPER: The most common mistake I see new investors make is assuming that the future will look like the past. To be more specific, new investors draw all sorts of faulty conclusions by assuming that the results of one particular period will look like the results of some other particular period.

New investors choose mutual funds based on past performance figures, despite the evidence showing that past performance is not a good method for predicting future top performers.

New investors read about the long-term historical returns of U.S. stocks and think that they should expect to earn such a return over their investment lifetime, despite the fact that individual investors can experience widely varying results depending solely on the year in which they’re born — something over which they have no control.

New investors will often look at a recent bear market and assume that the lesson to be drawn is that stocks are an undesirable investment going forward. Conversely, new investors will often look at a recent bull market and assume that they should expect stocks to keep going straight up. Then they’re shocked — and turned off of stocks — when they encounter their first bear market.

We can look at the past to get an idea of what can happen (tulip manias, for example). And, in some cases, we can look at the past to determine what tends to happen (e.g., lower-cost mutual funds outperforming higher-cost mutual funds). But looking at the past does not show us what will happen.

Mike Piper (@michaelrpiper) is a Missouri-licensed CPA and the author of the blog ObliviousInvestor.com. He is also the author of several personal finance books, including his latest, “Social Security Made Simple.”